bbPress is forum wordpress plugin which is used for creating a forum in a wordpress site. After installation of this plugin in a wordpress site it simply works. But there is no option in the plugin to adjust style. For this you need to manually edit bbpress.css file. Here is the process to adjust styling of bbpress plugin.
1. Install “bbPress Genesis Extend” plugin and Activate.
This will fix some style related issues that arise with bbPress and genesis theme integration.
2. Copy bbPress.css file to theme css folder.
Copy the bbPress.css file to your theme css folder. The full path would be:
copy /wp-content/plugins/bbpress/templates/default/css/bbpress.css to /wp-content/themes/yourtheme/css/bbpress.css
3. Make changes to the copied bbpress.css file as follows:
Replace all occurrences of:
font-size: 16px; to
font-size: 13px; to
font-size: 12px; to
font-size: 11px; to
font-size: 10px; to
For further reading check: bbPress Styling Crib